Double layered structures consisting of soft (S-) metal (Au, Ag, Cu, Al) films and hard (H-) metal (Cr) film were formed onto glass (G-) substrates by vacuum evaporation method. The adhesion characteristics of those structures were investigated by using the scratch tester developed by the present authors.
In case of S/H/G structures, the scratch peeling in the process of increasing loads was found to have two steps. Namely, S-film peeling at the S/H interface is occurred by comparatively small peeling loads followed by the H-film peeling at H/G interface by a larger load. On the other hand, the peeling of H/S/G structures has only one step. By applying a enough load to break the H-film, the double layers were peeled off at a time at the S/G interfaces.
The mechanism of the scratch peeling is discussed.